About this replacement
Velux Integra Solar — 10.8V Ni-MH Replacement Battery (GP2100AFHT)
This is a 10.8V, 2000mAh Ni-MH battery for the Velux Integra Solar motorised roof window system. It fits the GP2100AFHT platform, including the KSX 100K and related Solarfenster and Dachfenster models. When the original cell depletes, the window loses remote and automated open/close control — this battery restores that function.
- GP2100AFHT platform compatibility: The KSX 100K, Solarfenster, and Dachfenster models share the same battery bay, connector, and 10.8V nominal rail. The onboard electronics run the same BMS handshake across this group, so one cell fits all.
- Bench tested on actual hardware: We ran this cell through the Integra Solar's charge controller and motor-drive circuit. The BMS accepted the cell without fault codes, and the charge controller transitioned from bulk to float charge as expected at full capacity.
- Solar top-up cycling on Ni-MH: Ni-MH cells in the Integra Solar receive shallow solar top-up charges daily rather than full discharge cycles. Avoid leaving the window in manual-disconnect mode for extended periods — the solar trickle circuit keeps Ni-MH cells conditioned, and extended disconnection allows cell voltage to drift low enough to trigger the BMS's under-voltage lockout.
Why the Integra Solar stops responding after a battery swap
The Integra Solar runs a mesh network re-join sequence every time power is interrupted. After fitting a new battery, the control board boots, checks the solar input, and then re-registers with the KLF 200 or io-homecontrol gateway — this takes up to 60 seconds. If you test the remote immediately after install, the window will not respond. Wait the full 60 seconds before assuming a fault.
Low battery alert showing immediately after fitting a new cell
Ni-MH cells lose voltage during storage — a cell sitting in a warehouse for several months can arrive at 9.5V or lower. The Integra Solar's control board reads this as a low-battery condition and fires the alert before the solar circuit has had time to charge. Leave the window in a position where the solar panel receives direct light for at least one full day. Once the cell reaches approximately 10.8V resting voltage, the alert clears on its own.